1. Field of the Invention
This invention relates to a sheet feeding apparatus mounted to an image reading apparatus such as a copier, a facsimile, a printer or a scanner. More specifically, this invention relates to a sheet feeding apparatus comprising a support frame made of a plastic mounted to an upper portion of an image reading apparatus so that the sheet feeding apparatus can be freely opened and closed.
2. Description of the Prior Art
In a conventional image reading apparatus, in order to reduce a total apparatus weight, a frame is made of a plastic and provided with separating means to separate and feed sheets, transport means to transport the sheets to a platen on an image reading apparatus and a motor to drive these means. The frame is attached to a main body of the image reading apparatus by a hinge, which is disclosed in detail in Japanese Utility Model No. 2582475. The hinge has a spring that urges the frame in an opening direction so that the frame is freely opened and closed.
However, in the sheet feeding apparatus mentioned above, particularly in a flow-type sheet feeding apparatus wherein scanning means of an image reading apparatus is stationary and an image on a sheet is read while an original document is moving, a problem arises in that a proper reading of the original document is not made because of disturbance to an image upon scanning if a distance between a platen glass and the original document is not constant.
This is described in detail with reference to FIG. 7 and FIG. 8. FIG. 8 shows a sheet feeding apparatus mounted to an image reading apparatus via a hinge H provided with a spring S that urges the feeding apparatus in an opening direction. As shown in FIG. 8, when the sheet feeding apparatus A is closed over the image reading apparatus, it transports a sheet of paper to a platen glass G. Scanning means, not shown in the drawing, positioned below the platen glass G reads an image on the sheet as the sheet is transported over the platen glass G.
At this time, to maintain a constant distance between the platen glass G and a sheet guide SG that guides the sheet, positioning protrusions P1 and P2 are mounted at both edges of the sheet feeding apparatus A perpendicular to the sheet transport direction. The positioning protrusions P1 and P2 protrude toward the platen glass G beyond the sheet guide SG to abut against the platen glass G.
However, as shown in FIG. 8, if the frame of the sheet feeding apparatus A is made of a lightweight material such as a plastic, the frame tends to bend near a mounting position of the sheet feeding apparatus A on the hinge apparatus H, thus only the positioning protrusion P1 abuts against the platen glass G, and the positioning protrusion P2 does not. In such a state, when a sheet is transported to the platen glass G, a gap between the scanning means and the original document is not maintained within a constant range, thereby causing distortion in an image.
In the particular case shown in FIG. 8, when the spring S in the hinge H urges the feeding apparatus A in the opening direction, a permanent deformation will develop in the frame over a long period of time because of the constant urging stress.
As a solution of this problem, for example, height adjustment means HA comprising a spring is disposed in the mounting member HT as shown in FIG. 8. The height adjustment means HA lowers a side of the sheet feeding apparatus A where the positioning protrusion P2 is disposed. However, while the height adjustment means HA works to some extent, an adjustment will no longer work when the frame itself is deformed.
On the other hand, it would be possible to make the frame body of a rigid material such as steel, but a frame made of steel increases cost and weight.
In view of the aforementioned problems, an object of the present invention is to provide a sheet feeding apparatus provided with a frame made of a plastic with reinforcement to have enough rigidity to properly transport original documents without distortion of an image thereon.
The second object of the present invention is to provide a sheet feeding apparatus using a motor attachment member as a frame reinforcement member to reduce a cost.
The third object of the present invention is to provide a compact and lightweight sheet feeding apparatus with specially designed hinge members and motors.
Further objects and advantages of the invention will be apparent from the following description of the invention.
In order to attain the aforementioned objectives, the present invention provides a sheet feeding apparatus disposed on an image reading apparatus so that the sheet feeding apparatus can be opened and closed freely. More specifically, the sheet feeding apparatus comprises transport means for transporting sheets to a reading position; a support frame made of a plastic for supporting the transport means; a sheet stack unit for storing sheets disposed in the support frame; a hinge member mounted to the support frame; and a motor mounting member to support a motor that drives the transport unit. The motor mounting member is disposed in the support frame between the hinge member and the transport member as a reinforcement member.
Furthermore, the sheet feeding apparatus of the present invention is equipped with an adjustment member on the hinge member or between the hinge member and a main body of an image reading apparatus to adjust the height of the reading position and the transport member.
Also, the hinge member and the motor mounting member are connected by a connecting member.
Furthermore, the sheet feeding apparatus of the invention has a first connecting member for connecting the hinge member and the motor mounting member, and a second connecting member for connecting the motor mounting member and the transport member. The sheet feeding apparatus also has a transmission member to transmit motor drive to the transport member disposed between the motor mounting member and transport member.
The sheet transport apparatus of the invention comprises a transport member to transport sheets to the first reading section on an image reading apparatus unit; a sheet pressing plate to press sheets onto a second reading section on the image reading apparatus unit disposed adjacent to the first reading section; a support frame made of a plastic to support the transport member and the sheet pressing plate; a first hinge member mounted to the support frame on the transport member side and a second opening; and a second hinge member mounted to the support frame on the pressing plate side. The motor mounting member is disposed in the support frame between the first hinge member and the transport member as a reinforcement member. The sheet transport apparatus is also provided with a connecting member to connect the first hinge member and the motor mounting member at an upper portion of the support frame.
According to the present invention, because the mounting member for supporting the motor that drives the transport member is attached to the frame as a reinforcement member, even if the frame is made of a plastic, it reinforces a portion of the frame that affects the reading accuracy. Therefore, no other special reinforcement means is needed, so that the invention can provide a sheet feeding apparatus that can properly read originals.
Also, because the closing means and the motor mounting member are connected, the frame reinforcement is more enhanced.
Also, because the motor drive transmission means is disposed between the motor mounting member and the transport member, further frame reinforcement and effective use of space are possible.
In addition, this invention provides a sheet feeding apparatus comprising a transport member to transport sheets to a reading position to real images; a support frame made of a plastic including a sheet stacker for storing sheets; a hinge member that can open and close the support frame on an image reading apparatus unit attached between the transport member side and the sheet stacker side; a first motor to drive the transport member to transport sheets to a predetermined position disposed between the transport member and the hinge member on the transport member side; a second motor to drive the sheets from the predetermined position; a motor mounting member to support the first and second motors attached to the support frame as a reinforcement member. The first and second motors are disposed on both sides of the hinge member of the transport member.
In addition, the hinge member on the transport member side of the sheet feeding apparatus and the first and second motors are disposed to overlap each other in the height direction.
The hinge member on the transport member side of the sheet feeding apparatus is provided with an elastic member urging the sheet feeding apparatus in the opening direction. The hinge member on the sheet stacker side is provided with an elastic member that has an elastic force lower than that of the hinge member on the transport member side.
In addition, the hinge member on the transport member side of the sheet feeding apparatus according to the invention is provided with an elastic member urging the sheet feeding apparatus in the opening direction, and the hinge member on the sheet stacker side is not provided with an elastic member.
Thus, according to the invention, because the motor mounting member is also a reinforcement member, the frame has a stable balance without a twisting or deformation thereof when closing. Thus, it is possible to provide a sheet feeding apparatus that can properly read images.
Also, because the closing means and motors are overlapped in the height direction, it is possible to reduce a size of the sheet feeding apparatus in the height direction thereby attaining a compact and lighter structure for the overall apparatus.
Also, because the motors are disposed on both sides of the one of the closing means, a weight balance is stable. Furthermore, it is possible to lower the elastic force of the closing means of the other side or to omit it altogether, thereby providing a sheet feeding apparatus that reduces the cost without a decrease in reading accuracy.
It is obvious that any image reading apparatus equipped with the sheet feeding apparatus of the invention can attain the same effects.